The purpose of the present invention is to produce a non-reversible disposable syringe which retains the basic physical and operational characteristics of existing disposable syringes, yet after use is unable to be reused. It is also important that the device be capable of being mass produced economically using existing tooling and manufacturing techniques.
The syringe of the present invention is the same size as existing syringes and can be made as economically as existing syringes, and is tamper resistant. When used with associated features such as a disposal sleeve, the present invention provides a completely new medication delivery system which is safe and sterile from beginning to end.
Over the years, several attempts have been made to design and produce a syringe of this type. These attempts have, to date, been unsuccessful primarily because they did not achieve either the operational goal or the commercial goal. The annual production of disposable syringes numbers in the billions. For example, there are approximately 20 million diabetics in the United States. On the average each diabetic needs two syringes per day, which constitutes a need for over 16 billion syringes for diabetics in the United States alone. This figure does not include uses other than for diabetics, so the need for safe, effective syringes is extremely large. Generally, non-reusable syringes were restricted to pre-loaded syringes, or units with unusual or complicated operations. However, no significant medical or commercial success has been achieved to date by non-reusable syringes currently available.
The underlying goal of the present syringe is the prevention of user self-infection or the spreading of infection by the sharing of syringes, such as is caused by intravenous drug users and abusers.
A number of devices in the past taught a variety of mechanisms to destroy the syringe after use. For example, U.S. Pat. No. 3,951,146 to Chiquiar-Arias positions a blade inside the syringe in such a way as to slice through the syringe during the injection sequence. This device would be cost prohibitive to manufacture and sell due to the structure needed to make the syringe non-reusable. U.S. Pat. No. 3,998,224 to Chiquiar-Arias causes the syringe to be punctured at the end of the injection sequence. Further, there is a small embossed stop at the bottom which captures the push rod at the bottom of the cylinder. It also proposes to plug the needle at the end of the sequence. There is no comparison in operation or structure to the present invention.
U.S. Pat. No. 4,233,975 to Yerman proposes a mechanism which irreversibly clogs itself upon use, but the injection sequence must go to completion to be effective. It also proposes a spring loaded latch which pops into a notch at the bottom of the syringe. It also invokes other locking mechanism which prevent the re-use of the syringe. However, all these mechanisms require special loading and/or for the injection to go to completion, unlike the present invention.
A number of devices utilize pre-filed syringes. For example, U.S. Pat. No. 4,367,738 to Legendre et al. is a one-way pre-filled syringe and has no commonality operationally or mechanically with the present invention. Furthermore, the Legendre et al. device would be difficult to manufacture in comparison to the present invention. U.S. Pat. No. 4,493,703 to Butterfield proposes a syringe using a pre-loaded drop-in cartridge injected via a one way drive piston. This device has no commonality in operation or mechanics with the present invention. U.S. Pat. No. 4,713,056 to Butterfield also proposes a unit that must be pre-loaded. The injection operates via a one-way piston with a latching device which depends on grooves in the barrel of the syringe to guide and capture the piston. This device further uses a pawl mechanism unlike the present invention.
U.S. Pat. No. 4,775,363 to Sandsdalen discloses a self-releasing piston having a different functional implementation. Sandsdalen depends on certain forces being present to deform various of its components to effect the piston's release. The present invention's operation does not depend on injection forces and will operate consistently.
U.S. Pat. No. 4,775,364 to Alles discloses the use of molded-in guides and catches, suction cups, with a break-away push rod to accomplish its goal of non-reusability.
U.S. Pat. No. 4,781,684 to Trenner employs a number of notches in the wall of the barrel to catch flanges on the piston to disable the syringe after use. This is also dissimilar to the present invention.
U.S. Pat. No. 4,820,272 to Palmer utilizes a series of catches, and the unit must be fully injected to lock up the syringe. The device provides tactile feedback to warn the user of impending lock-up. This is done to prevent lock up during the filling operation. This feature almost entirely defeats the purpose of the non-reusability.
A number of devices utilize complicated and expensive structure. U.S. Pat. No. 4,826,483 to Molnar, IV disclosed a complicated arrangement of dual sets of ratchets. U.S. Pat. No. 4,840,616 to Banks uses a series of teeth and splines activated by requiring the user to rotate the plunger. Both are highly dissimilar in operation and structure to the present invention.